


I Love You, Little Brother

by DandelionSea



Category: Underswap (Fandom), Undertale (Video Game)
Genre: Alternate Universe - Underswap, Angst, Babybones, Brothers, Drama, Emotional Hurt/Comfort, Family Feels, Fluff
Language: English
Status: Completed
Published: 2018-02-14
Updated: 2018-02-14
Packaged: 2019-03-18 11:16:02
Rating: General Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 3,776
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/13680582
Author URL: https://archiveofourown.org/users/DandelionSea/pseuds/DandelionSea
Summary: Papyrus didn’t like that his dad was making another baby.





	I Love You, Little Brother

**Author's Note:**

  * For [Redo_Reset](https://archiveofourown.org/users/Redo_Reset/gifts).



> Happy Valentines Day to my best friend [Redo_Reset](http://archiveofourown.org/users/Redo_Reset/pseuds/Redo_Reset), who told me last night that they needed more baby US!Sans and angst in their life. 
> 
> <3

Papyrus didn’t like that his dad was making another baby.

Skeletons had gone almost extinct when monsters were forced underground; more accurately, they died off  _ before _ then - back during the war when they charged the front lines in battle. By the time the humans took their victory and marched the monsters under the earth’s crust there was only one skeleton left: Wingdings Gaster. The queen and king took him in, as he was only just reaching adolescence at the time. They provided him with a family and helped find ways to educate him while the monsters were busy rebuilding their society. To pay them back for this kindness Gaster dedicated his entire life in service to the kingdom, finding ways of generating power underground, practicing medicine, training and teaching new scientist… by the end of his third century Gaster had become one of the most influential monsters to ever live.

Which is why only a few decades later, he stepped down from his position as royal scientist, handing it off to a promising young student of his. He was sad to leave, and certainly the queen had begged him to stay - he never even fully left the department, working part time on weekdays; but most of his time he spent on a personal project. Something he had been planning for a long time. He told no one of it, letting them all wonder about what it could possibly be that the famous scientist was working so hard on in his basement. Could it be a way to break the barrier? A new security system to prevent human attacks? 

In reality, it was something more… personal.

Truthfully, Gaster told no one of his project because if it failed he would be unable to handle the pity and sorrow that his friends and colleagues would put on him; but upon its success he was very open to show off the results of his labor.

No one really knew what to think when Gaster walked into the lab monday morning, a tiny skeleton hidden behind his pant leg, clutching his father’s hand like a lifeline. Children in the underground are somewhat rare these days, since it requires an excess of hope in one’s soul to naturally conceive. With hope levels on the decline most monster parents now owe their children to artificial means; however they still need two parent donors to create a new child. Gaster, by a miracle and hard work, was able to bypass the necessity for another skeleton, and created a small, genetically unique clone. 

He named the child Papyrus, after his font.

Papyrus became very popular very fast; the documentation of his unique conception was published shortly after his “birth” in hopes of helping other monsters who lack a spouse. The scientific curiosity in him lasted for only a few months, though, as the department became used to his presence in the labs. An empty office was set up for Papyrus to use as a playroom, filled to the brim with science toys and puzzles. Many of the scientists took their breaks with Papyrus, taking him to the cafeteria and chatting with him. Much of his early education was gained from these conversations, as well as his social skills and general sense of humor. 

Once as Papyrus got to an age where he can be more independent, Gaster started to shift back into full time work. He now has a child to support, and he refused to take money from the Queen, despite her insistence that she is the boy’s great-aunt (though Gaster appreciated the relationship she formed with his son. He knows how hard it’s been on her since she lost her own child). Gaster also made the decision around the time that Papyrus was entering grade school to move their home to Snowdin - it’s farther from work and the capital, but there are more children and better schools there.

Papyrus was not happy when he started kindergarten. 

He would cry almost every day on the way to class, refusing to let go of his dad’s hand. Despite making several new friends and enjoying the classes, he didn’t like being left behind. He had never been away from his father before, and he missed going to the labs. Gaster gave him more than one stern talking to, letting him know exactly what was expected of him now that he was moving away from being a babybones.

_ “One day you will be an adult, Papyrus, and adults do not pitch fits when they go to school,” Gaster told him. “You want to be a grown bones, don’t you?”  _

_ “no! i wanna go to work with daddy!” Papyrus sobbed, grabbing on to Gaster’s coat so that he can’t leave.  _

This was their rotunene for almost a year. Gaster went to the queen more than once to ask guidance over tea, head in hand. 

_ “He is a mess, Toriel, I don’t know what to do,” He said, taking off his glasses to pinch the bridge of his nose.  “He refuses to go quietly to class, He refuses to let me work when I am at home, he refuses to let me sleep - it is as if every minute I spend with him just isn’t enough!” _

_ Toriel just laughed. “That’s children for you…”  _

Slowly, Papyrus became more independent. Gaster would send him to the bus in the morning with a lunch already packed, barely having any time for breakfast as his son would wake up only five minutes before it was time to go. When Papyrus got home he would instantly go to his room for a nap, waking up in time for dinner and TV before returning to bed. There routine changed from there as slowly Papyrus went from needy to distant, hardly saying a word to his father when they were at home together. He started sleeping over at friends houses, skipping breakfast and dinner - It wasn’t a change that Gaster appreciated. He missed his son, but a part of him understood that Papyrus was growing up, and that the relationships he was forming with other children were healthy, and that he should be proud. 

And then came the day that Gaster announced there was going to be another baby. 

He had been working on the logistics of it for a while, gathering materials and equipment and going over his notes. Really, he should have done this years ago when the process was still fresh in his mind; though he had been so busy taking care of this first child, he didn’t want to risk being neglectful. 

When the team found out he was congratulated, and Toriel practically forced him to take time off to prepare.

However, Papyrus’ reaction wasn’t what Gaster had been expecting at all.

He decided to tell him over dinner, thinking that it would be the best time since Papyrus wouldn’t be sleepy or preoccupied with school. Gaster watches his son pick at his peas - even though he has grown so much over the years, Gaster still can’t seem to find an efficient way to get his child to eat his vegetables. Gaster has already cleared his plate, tapping at the table with his fingers. His eyes glance at the clock; it’s almost 9:30. Papyrus will be heading to bed soon. Gaster sighs. He has to say it now or never.

“Papyrus, how would you feel about having a little brother?” 

The ensuing silence is broken only a second after it started by the clink of a fork dropped on porcelain. 

“...what?” Papyrus asks slowly. His expression is completely blank; it becomes painfully obvious that he’s horrified. His eye sockets go dark. Normally Gaster would scold his son for using his “scary eye” at the table, but he gives it a pass to continue the conversation. 

“I have begun the process to create another child, the same way I created you,” Gaster explains. “He will be finished in a month’s time. I was hoping maybe you could-”

Gaster cuts off as Papyrus teleports away. He sighs, standing up to clear the table. He’ll call Undyne’s house to see if he went to stay with her; that seems to be his normal hiding place these days. The daughter of his colleague has become one of Papyrus’ closest friends, despite the fact that she goes to a different school. 

The next few weeks Gaster sees very little of his son. 

Papyrus goes straight from school to Undyne’s. If he doesn’t go there then he goes to another friend, and barring all else he simply goes directly to his room. The only times he dares show his face in the living room is to do laundry - and even then that he only does that once in the ensuing weeks of silence. Gaster is almost proud that Papyrus remembered to do his laundry at all this month.

Finally, he catches Papyrus on his way up the stairs after school. He grabs his soul with blue magic just to be sure he doesn’t teleport away. Gaster only does this when he’s upset... Papyrus flinches and slowly turns around, expecting to be in trouble.

“Come with me,” Gaster says, walking out the front door to the basement. He picks his son up when he realizes that the boy is only wearing slippers, making sure that his feet aren’t soaked by the snow. 

He puts Papyrus back down when they get inside the heated basement, walking forward until they reach a tube. It is the same one where Papyrus was incubated, though the solution recipe has been modified some with adjustments that Gaster discovered after his first experiment. Papyrus slowly walks up to stand beside his father, looking into the tube with wide eyes.

Inside the blue, swirling liquid, is a very,  _ very _ small skeleton. 

“This is your baby brother,” Gaster says. “I haven’t been able to observe his font yet, however since I did not have much physical matter left to donate he will be quite small. I imagine his font will be some sort of Sans Serif.” Gaster pauses. “...Tomorrow I plan to take him out of suspension.”

Papyrus is completely silent, for once not finding some clever comeback, or sarcastic remark, or even a witty pun. He just stares openly yet without betraying his emotions, taking in the tiny bones of his infant brother suspended in the cyan mixture. 

“he’s... different from me,” Papyrus says slowly. Gaster nods.

“Yes. His DNA was synthesized from my own, however just like you it is completely unique to him,” Gaster explains, hoping that somehow that would relieve the mildly horrified expression on his son’s face. Somehow his explanation only makes it worse. 

“why is his magic different?” Papyrus asks, pointing at the blue swirls surrounding the baby.  

“I modified the procedure slightly,” Gaster admits. “Because you were the first attempt at such an experiment there were certain variables I did not take into account, therefore my method could be improved by using what I know now from my last attempt.”

The calm, rational statement is enough to put Gaster’s mind at ease, but the same cannot be said for his son, whose eyes suddenly fill will tears. Gaster briefly hopes that it just means his child is moved by the creation of life before him; however that fantasy is completely dashed upon further examination. Papyrus is shaking, fists balled as his face contorts into pure agony.

“Papyrus?” Gaster frowns, turning to his son. 

Papyrus suddenly turns to Gaster, plastering the largest fake-smile he can muster. “i’m happy for you, dad. i hope he’s everything you ever wanted.”

And with that Papyrus disappears.

* * *

Under the covers of a race-car bed, a flashlight is held by a bony hand. Papyrus’ eyes scan the words stacked neatly on top of each other printed on the five-hundred-and-sixty-second page of his joke book. It was a present for his birthday last month, and since then he has read the entire book cover-to-cover at least a dozen times. Most of the jokes he has memorized, though sometimes he can find one he’s forgotten and still get a chuckle out of.

This time, though, the book does little to excite his sense of humor.

A baby. His father made another baby.

Papyrus fights back tears as his hands flip to the cover page of his book. He knows better, and yet his eyes immediately go for the set of words scrawled in handwritten font under the author’s name.

_ To my precious son.  _

_ May this book bring you as much joy as you have brought me _ .

Papyrus keens, clutching the book to his chest as he doubles over and sobs. 

Was it all a lie then? Papyrus is supposed to be the perfect child, and yet he has done nothing but fall short of that image. He tried so hard to be everything that his father wanted, but it just wasn’t in him. He failed. He failed so badly that apparently his dad felt it was necessary to create an new child to improve upon Papyrus’ failures.

Papyrus is sure his dad will love the new baby more than him.

It’s a given.

Papyrus falls over on his side, closing his eyes. He skipped school today - not even bothering to go downstairs for the bus. His dad didn’t force him to go either, simply knocking on the door when it was time for lunch, leaving a PB&J sandwich by the door when Papyrus refused to come down. 

If the clock on the wall says the right time, then it is only about an hour before dinner. Papyrus feels his stomach growl. Somehow doing nothing has worked up his appetite. He slowly rolls himself out of bed, letting his legs get tangled in the sheets so he pulls them all off the mattress as he tumbles to the ground. Papyrus hasn’t even changed out of his PJs yet and he doesn’t plan to as he opens the door and walks down the stairs. 

He is, admittedly, a little shocked to see Aunty Toriel downstairs. She comes over for holidays and birthdays, and occasionally just to visit, though normally Papyrus is told some time in advance. He’s never just… walked into a room with people unexpectedly there. It’s startling.

Toriel is seated on the couch next to Gaster, the two of them huddled around something. Papyrus can guess what it is, though he still walks forward, craning his neck to get a decent look at his replacement. 

Toriel turns before he can see, smiling wide. There are tiny tears tracking down her face, and briefly Papyrus wonders why _ she _ ’s the one crying here.

“Oh Papyrus, my child,” She says, standing suddenly to hug him. “Congratulations! This is wonderful, truly wonderful.” 

Papyrus can’t imagine what could be so great about this development for him, but Toriel seems really happy, and he can’t deny her that. He loves his Aunty too much for it. His arms wrap tightly around her and he takes comfort in the embrace. Somehow her hugs always make things feel better.

Finally, when Papyrus is let go, he gets to look at the baby. 

He feels his soul skip a beat. 

In the tube, the baby looked almost hideous - a little collection of bones balled up in a practically amorphous blob suspended in a sea of blue. Papyrus had been admittedly horrified not just by his little brother’s existence but by the way he looked. Was that truly the creature his father intended to he his improvement??

But the baby doesn’t look like that any more. 

The baby looks like, like well a  _ baby _ . With rosy cheeks, squishy features, a round belly covered by a tiny onesie, and a precious smile. Gaster has his arms wrapped around the infant, feeding it an equally tiny bottle of magically-infused milk. The baby’s hands fly up, grabbing at his arm. It takes Papyrus a moment to realize the baby is pushing Gaster’s hands away so he can see Papyrus. 

Without meaning to Papyrus’ eyes light with magic. 

Gaster smiles, watching Papyrus’ awestruck face as he turns, removing the bottle from the baby’s mouth and sitting him up. “He’s a Comic Sans,” Gaster says quietly, holding the infant out for Papyrus. “Would you like to hold him?”

Papyrus almost wants to refuse, afraid that he will either drop the baby, or hold him to tight, or do  _ something else _ that might endanger the precious child being entrusted in his care. However before he realizes what happened he is sitting down on the floor with his baby brother in his arms. 

He looks down at the tiny creature. Gaster has him wrapped tightly in a baby blue blanket that matches his magic perfectly. His eyes are huge - much bigger than either Gaster’s or Papyrus’ - and they each have tiny stars in them. Papyrus didn’t even know that was possible for a skeleton!! The baby has a corner of the blanket in his mouth, chewing on with chubby cheeks it as he observes Papyrus. Without warning the baby lets out a high-pitched shriek, giggling as he lets the blanket fall away from his mouth and pats Papyrus’ cheeks. 

Papyrus feels tears on his cheeks once again, though this time he can’t be sure which emotion is causing them.

All too soon his dad reaches down to collect the baby - Comic Sans, if Gaster decides to go with a traditional skeleton name. Papyrus watches Comic be collected up, slowly dozing off in his - in  _ their _ \- father’s arms. Gaster smiles, looking down at his eldest son.    


“I knew you would love him, once as you had the chance to meet him, that is,” Gaster says, rocking the baby. “I felt the same way when you first came out. I couldn’t stop looking at how perfect you were.”

Papyrus feel his soul crushed under the under, contrary to the nature of the statement. He hangs his head, trying so hard not to cry. It only makes him cry harder. Toriel comes down by his side, holding him back in a hug. 

“My child, what is wrong?” Toriel asks in a soft voice. “You should be happy - a younger brother is a gift.”

Papyrus shakes his head, not sure if he is replying to the comment or rejecting the comfort all together. He looks back up at is father, his miserable eyes meeting the strong, concerned gaze of his dad.

“does this mean you don’t want me anymore?” Papyrus asks, shaking slightly as he does. Gaster’s eyes widen, stunned horrified by the sincerely asked comment.

“Papyrus, how could you even think such a thing?” Gaster says, handing off the sleeping infant to Toriel as he kneels down to the level of his first child. Papyrus attempts to look away, but Gaster takes his chin and slowly turns it up. “I love you; more than anything else in the entire world.” 

“except the new baby,” Papyrus mutters, curling up on himself. Gaster shakes his head, pausing for a moment to collect his words. Toriel stands and goes to the kitchen to get another bottle (and to give the two some privacy). Gaster quickly picks up his son and puts him down on the couch so that he can sit next to him comfortably. 

“Papyrus, do you know why I made another child?” Gaster asks. Unsatisfied by the half-shrug he gets in response, he rephrases. “Why do  _ you _ think I created the other child?” 

“... because you wanted a better son?” Papyrus mumbles, hugging his knees.

Gaster shakes his head. “Why on earth would you think that?” Papyrus shrugs again, causing Gaster to sigh fondly. He wraps his arms around Papyrus, who, after a moment of hesitation, leans into the affection. Gaster rests a hand on Papyrus’ skull as he continues. “Papyrus, I created this child for you.”

Papyrus startles, looking up at his dad. “...w-what?” 

Gaster smiles, nodding. “Did you enjoy holding your baby brother?” He prompts. Papyrus nods. “Are you excited to be an older brother.” 

“...i… i guess?” Papyrus says. Honestly, he hadn’t given it much thought until now, to focused on the fact that was his replacement to think about if he would  _ enjoy _ having a baby brother around. 

Gaster sighs, looking off into the distance. Sometimes Papyrus doesn’t know what his father is looking at when he does that. Though perhaps he will get some insight as his dad starts talking once more,  “... A long time ago, I had siblings,” Gaster explains. “I don’t remember them well, however they were the ones to raise me. To be there for me - and when another came along younger than I - I was the one to care for him…” There is a pause. “Traditionally, skeletons have very large families… at least, we used to. Now there is just us.” Gaster turns to Papyrus. “I won’t be here forever, my son. Skeletons live a long time, yet we are not immortal; I will not have you be alone like I was. Sans, your younger brother, will be your company. He will be with you for the rest of your life; your companion, your best friend. One day, when you are older, I will teach you how to create children of your own; you will not be alone when you raise your children, like I was. You will have Sans with you to help guide you, to share the attention, the burdens. He will be your family, as I am to you, and as Toriel is to me.” 

Papyrus is shaking, watching his father's’ face for a long time before he slowly leans forward and presses himself into Gaster’s sweater, letting out the hardest sobs of his life. 

The two stay like that for a long time, eyes lit, until Toriel returns with Sans. She apologizes for her early departure, returning the baby to Gaster and bidding Papyrus a fond goodnight. Gaster has dinner already prepared in the kitchen, waiting to be served. Papyrus holds onto his new baby brother the entire time, eating his pasta with one hand while rocking his brother with the other. Sans stirs at some point and coos up at Papyrus, wiggling his hands and feet as he tries to play for the first time in his short life. 

Papyrus eventually starts to dose after a while, and Gaster moves the boys to the couch in the living room. Gaster quietly watches the baby nuzzled into Papyrus’ sleeping arms, smiling down at his second son as he too has fallen asleep. His hand rests on Papyrus’ head, humming to himself as he watches over his tiny family all together in one room. 

**Author's Note:**

> I'll go back and edit this later, since this was written entirely last night and I haven't had time to sit down and look it over lol.


End file.
